Electrolysis



Jan. 13, 1931. P. FIREMAN 1,788,512

ELECTROLYSIS Filed May 9. 1927 3 Sheets-Sheet 2 DISEDIZIEIZEEDDEEEEEEEUQGEDEDE EDCIEEEEGEEEEE INVENTOR ATTORNEYS Jan. 13, 1931. P.FIREMAN 1,788,512

' ELECTRQLYSIS Filed May 9. 1927 SSheets-Sheet 5 INVENTOR BY rCQm/vATTORNEYS Patented Jan. 13, 1931 UNITED STATES PATENT OFFICE y PETERFIREMAN, OF TRENTON, NEW JERSEY, ASSIGNOR TO MAGNETIC PIGMENT COM-PAJSIY, OF NEW YORK, N. Y., A CORPORATION OF NEW YORK ELECTROLYSISApplication filed Ma 9, 192%. Serial no. 189,822.

This invention relates to electrolysis, and particularly to theproduction of alk all'es and metallic salts in a single electrolyt1coperation, the alkali and salt solutions being -re- 5 coveredseparately. I

In the production of metalllc salts and alkalies by electrolysisdifficulty is encountered because of the interdifl'usion of-theseproducts. Thus, if ferrous chloride and sodium 1 hydroxide, for example,are produced 1n the same cell the interdiffusion results in aprecipitate of ferrous hydroxide. The accumulation of such a precipitatein the cell rapidly reduces the efliciency thereof. The cell '15 quicklybecomes inoperative and must be emptied and cleaned.

In United States Letters Patent No. 1,490,- 372, issued April 15, 1924,I have described an electrolytic cell and the method of operating such acell to produce solutions of metallic salts and of alkalies such, forexample, as ferrous chloride and sodium hydroxide by electrolysis of asolution of sodium chloride in the presence of an iron anode. The celldescribed in the patent is divided by a separator into anode and cathodecompartments. The separator permits operation for more or lessextendedperiods by limiting the interdifi'usion of the products in the anodicand cathodic compartments. Nevertheless interdifiusion occurs to asufiicient extent so that operation of the cell must be stopped more orless frequently for cleaning.

It is the object of-the present invention to. avoid the difficultyexperienced in the opera- .tion of cells of the character described andto permit substantially continuous operation thereof for much longerperiods by preventing the interdifiusion of the anode and cathodeliquors in' a more thorough manner. A further object of the invention isthe provision of an improved electrolytic *cell and of a novel method ofoperating such a cell to permit the simultaneous production of solutionsof alkalies-and of metallic salts in a substantially continuous manner.

I have discovered that interdifi'usion in electrolytic cells designed topermit the production of solutions of metallic'salts and the alkaliescan be prevented by maintaining an independent body of the electrolytebetween the anode and cathode compartments and by constantly renewingthis body of electrolyte. This independent protecting body ofelectrolyte provides a meeting place for the metallic salt and alkalidiflt'using from the anode and cathode. The incipient precipitate in theprotecting body of electrolyte is swept out by the continuous withdrawalof this electrolyte. Ordinarily the electrolyte withdrawn from theprotecting body contains a little of the metallic salt and no alkali. Itis possible thus to prevent the concentration of the metallic salt inthe protecting body of electrolyte from increasing beyond from 0.1 to0.3 normal while the anode liquor is'from 2 to 3 normal.

In carrying out the invention I provide a cell having preferably. acentral anode and a perforated cathodes at the sides thereof with 70 Idiaphragms such as asbestos sheets disposed at the cathodes, to limitthe flow of the electrolyte therethrough. I provide in addition spacedseparators between the anode and cathodes. These separators may be madelikewise of asbestos sheets or of asbestos and paper with a fabric suchas burlap. The separators are spaced apart, for example, aboutfive-eights of an inch so as to form an intermediate compartment betweenthe anode and cathode compartments. Each of the individual compartmentsis supplied constantly with the electrolyte from sources maintained ataconstant level so as to ensure the same head of liquor in eachcompartment. Provision is made for the withdrawal constantly of theanode liquor and of the electrolyte from the intermediate compartmentsSuch'provision may include outletpipes with nozzles of predetermineddimensions designed to ensure a constant flow of the desired proportion.The electrolyte which passes through the cathode diaphragms is likewisewithdrawn as it is formed and constitutes the alkali solution which isone of the products of the operation. The constant flow of theelectrolyte through the intermediate compartments ensures the,

. maintenance therein of protecting bodies of which may be su nated withthe anode liquor. The formation of precipitates in the anode and cathodecompartments is thus avoided and the operation of the cell is improvedmaterially.

The invention as described can be utilized in various electrolyticoperations wherein it is designed to produce simultaneously solutions ofcompounds which would react if permitted to contact with each other. The

invention is particularly useful in the production of solutions ofalkalies and of metallic salts, for example, the electrolysis of sodiumchloride in the presence of an iron anode to produce ferrous chlorideand sodium hydroxide as described in the Letters Patent aforesaid. Otherelectrolytes may be used, however suchas sodium sulphate bstituted forsodium chloride. Similarly other soluble salts of the alkali metals suchas sodium nitrate, sodium bromide, sodium acetate, potassium chloride,

- etc., may be electrolyzed in the cell as described to producesolutions of the alkalies and of metallic salts. Moreover, by replacingthe iron anode b one of zinc, nickel or some other metal w ich forms achloride, sulphate or other salt, soluble in water but which is itselfinsoluble in'that menstruum, other metallic salts can be obtained alongwith the alkalies. The products may be recombined in accordance with themethod ofthe Letters Patent aforesaid and of other patents issued to meheretofore for the production of pigments by regulated oxidation of.freshly precipitated ferrous hydroxide.

. They may be used also for any other purpose for which they are adaptedand they are par- Fig. 5 'is a detail in'section showing theconstruction of one of the separators.

Referring to', the drawing, 5 indicates a base constructed-of concrete,for example, or

of other material which is not affected by the anode liquor A pluralityof rods 6 extend upwardly from the base'and support a frame 7 formingthe top of the cell. A plurality of frames 8, 9 and 10 are supported onthe concrete base and are secured by clamps 11 thereto. I The frames areheld at the top of the.

cell by screws 12 supported in bars 13 which extend lengthwise of thecell on the frame 7. Plates 14 are secured to the sides of the cell andare held by the clamps 11 and screws 12,

ably of asbestos paper are likewise supported,

adjacent to the cathode plates 15 to limit the flow of the electrolytethrough the cathode plates.

' Separators 17 'are supported in spaced re lation by the frames 8 andform the intermediate compartments of the cell, the space between eachof the diaphragms 16 and the adjacent separators 17 being defined insuch a manner by the seperators that the electrolyte therein comprises acatholyte. These separators may be constructed ofany suitable material,but preferably may comprise an inner sheet of asbestos paper 18'withlayers 19 of cellulose paper thereon and protecting layers 20' of afabric such as burlap to give additional strength to the separators.

The anodes 21 are supported by holders22 in the anode compartment 23 andare connected by conductors 24 to a source of current of a charactersuitable for the practice of the electrolytic operation. The cathodes 15are likewise connected by a conductor 25 to the source of current. Inoperation the several compartments of the cell are supplied with theelectrolyte, for example, a saturated solution of sodium chloride fromconstant level containers 26 disposed at the ends of the cell. Theelectrolyte is delivered to these containers through pipes 27 andoverflows through orifices 28 to compartments 29 whence it may bereturned again to the constant level containers. The electrolyte entersthe several compartments through pipes 30, 31 and 32 provided for thatpurpose. The liquor in the'anode compartment which, in the case of ironanodes and a sodium'chloride electrolyte, consists of a concentratedsolution of ferrous chloride, descends into a chamber 33 in the base 5and escapes through an outlet 36 having a nozzle 37 at the end thereof,the orifice of which is of such size as to ensure the continuous flow ofthe desired proportion of the anode liquor from the cell. Similarly theelectrolyte which enters the intermediate compartments flows therefromconstantly through an outlet 38 having a similar nozzle v39 to ensurethe constant flow of the desired are maintained between the anode andcathode compartments. Fresh electrolyte is delivered'constantly to theintermediate compartments, and being substantially free from the saltproduced in the anode compartment or containing only a very lowconcentrationof such salt, it efl'ectually prevents diffusion of thatsalt into the cathode compartment and avoids the separation of anappreciable precipitate therein. Diffusion of the alkali into the anodecompartment is prevented similarly. Consequently, when properl operatedthe cell as described can be used or long periods without the necessityof dismantling it for cleaning, it being necessary only to renewtheanodes as they are dissolved and to ensure the maintenance of freshelectrolyte in the intermediate compartments. Another advantage ofthe-cell is its simplicity of construction and the relatively slightattention which. it requires during operation. The rate of outflow ofthe solutions when once determined remains fixed and a constant head ofelectrolyte is supplied to all of the compartments from the constantlevel receptacle. Consequently it is necessary only to ensure a supplyof the electrolyte to the constant level compartments and themaintenance of the current supplly. The only other attention required ist e renewal of the anodes as the latter are used u While I haveplication of the invention to the production of ferrous chloride andsodium hydroxide, it is to beunderstood that the invention has a broaderapplication and that, moreover, the

by the operation.

. structure of the cell may be varied to meet particular'requirements.The important features of the invention are the maintenance of theprotecting intermediate layers of the electrolyte between the anode andcathode compartments and the provision inv the cell for such layers andthe renewal thereof so that increase in the concentration of the saltproduced in the anode compartment may be avoided.

Various changes may be made, therefore,

i in the details of arrangement of the a parahis and in the mode ofoperation t ereof without departing from the invention or sacrificingany of its advantages.

1. The method of conducting electrolysis with a soluble anode, whichcomprises "continuously supplying fresh electrolyte to an in dependentbody thereof between bodies of T an electrolyte in contact with theanode and cathode, separately supplying electrolyte to the latterbodies'and continuously withdrawing a ortion of the electrolyte from the'indepen ent body ode orfcathode. o

2. The method of conducting electrolysis with a soluble anode, whichcomprises separating bodies of electrolyte incontact with the anode andcathode by an independent body I e'scribed the particular apbination,with a soluble anode of a perforated cathode atone side of the cell, aporous diaphragm closely adjacent the cathode, spaced porous separatorsbetween the anode and the porous diaphragm dividing the cell intoseparate anode and cathode compartments and formin an intermediatecompartment and means or supplying electrolyte to and withdrawingproducts separately from the several compartments.

. 4. The method of simultaneously producing solutions of metal salts-andalkalies which comprises electrolyzing a solution of an alkali salt inthe presence of a soluble anode and a cathode, separating the bodies ofsalt solution incontact with the anode and cathode by an independentbody which is constantly renewed without contacting the anode orcathode, and separately supplying'salt solution to the bodies thereof incontact with the anode and cathode.

In-testimony whereof I aflix my signature.

' PETER FIREMAN.

without contact with the anof electrolyte, withdrawing a portion thereofcontinuously without contact with the anode or cathode and replenishingthe independent

